Complinace with NEC-2017 Art. 240.87

[Leo1]

How can compliance with NEC-2017 Art. 240.87 be achieved? Will disconnect manufacturer's have energy-reducing maintenance switches by Jan 1, 2020? If not what are electrical designers, engineers and/or contractors doing now to meet the 240.87 requirements. Thank you. dis

 

[petersonra]

How can compliance with NEC-2017 Art. 240.87 be achieved? Will disconnect manufacturer's have energy-reducing maintenance switches by Jan 1, 2020? If not what are electrical designers, engineers and/or contractors doing now to meet the 240.87 requirements. Thank you. dis

I think what they are talking about is MCCB that can have a selectable instantaneous trip that can be switch selectable. During normal activities, a higher trip setting is selected. During maint activities, a lower instantaneous trip setting is switched in so the incident energy is reduced because the MCCB trips faster.

 

[Leo1]

I think what they are talking about is MCCB that can have a selectable instantaneous trip that can be switch selectable. During normal activities, a higher trip setting is selected. During maint activities, a lower instantaneous trip setting is switched in so the incident energy is reduced because the MCCB trips faster.

Agree - I believe concept you are correct. So how is this achieved by the designer/installer? I have contacted Schneider and it appears they now have main circuit breaker disconnect switches, with larger than non-arc energy reduction type enclosures, but no current solution for fused main disconnects that I am aware of. Getting back the main circuit breaker disconnect switches,the Schneider rep I spoke with told me the arc energy reduction type enclosures are rather large - more room space is needed.

 

[iceworm]

How can compliance with NEC-2017 Art. 240.87 be achieved? Will disconnect manufacturer's have energy-reducing maintenance switches by Jan 1, 2020? If not what are electrical designers, engineers and/or contractors doing now to meet the 240.87 requirements. Thank you. dis

Leo - You made made look. I didn't remember a time limit on 240.87. Did you mean 240.67?
240.87 is for CBs. 240.67 is for fuses.

240.87 Arc energy reduction (Circuit Breakers) Added to NEC 2011
Does not seen to apply to over 1000V - which is good
Most of 240.87.B. (1-7) is available.

Although I have not seen item 4 (energy reducing active mitigation) on systems 1000V or less. I have seen this on MV, but not on 480V. Doesn't mean it is not available - just means I haven't seen one.
And item 7 (approved equivalent) doesn't seem likely. Why would any AHJ go out on a limb and approve any thing not specifically listed in the NEC?​

240.67 Arc energy reduction (Fuses) Added to NEC 2017
I don't see this one going anywhere. I suspect the code panel is telling us to use CBs.
240.67.B

.1 Differential relaying - Okay, use CB around fuses. That makes no sense.
.2 Energy reducing maintenance switch - How does one switch a fuse? Electronically actuated fuse? Maybe, but I have not seen one for 1000V or less.
.3 Active arc flash mitigation - Certainly possible. As noted I have not seen it yet for 1000V or less.
.4 Approved equivalent - not likely.​

So, pick fuses that will clear is 70 ms or less, or don't use fuses.

This is where someone jumps in and explains the errors in my reasoning. And that is okay. I'm absolutely open to learning.

the worm

 

[Leo1]

Leo - You made made look. I didn't remember a time limit on 240.87. Did you mean 240.67?
240.87 is for CBs. 240.67 is for fuses.

240.87 Arc energy reduction (Circuit Breakers) Added to NEC 2011
Does not seen to apply to over 1000V - which is good
Most of 240.87.B. (1-7) is available.

Although I have not seen item 4 (energy reducing active mitigation) on systems 1000V or less. I have seen this on MV, but not on 480V. Doesn't mean it is not available - just means I haven't seen one.
And item 7 (approved equivalent) doesn't seem likely. Why would any AHJ go out on a limb and approve any thing not specifically listed in the NEC?​

240.67 Arc energy reduction (Fuses) Added to NEC 2017
I don't see this one going anywhere. I suspect the code panel is telling us to use CBs.
240.67.B

.1 Differential relaying - Okay, use CB around fuses. That makes no sense.
.2 Energy reducing maintenance switch - How does one switch a fuse? Electronically actuated fuse? Maybe, but I have not seen one for 1000V or less.
.3 Active arc flash mitigation - Certainly possible. As noted I have not seen it yet for 1000V or less.
.4 Approved equivalent - not likely.​

So, pick fuses that will clear is 70 ms or less, or don't use fuses.

This is where someone jumps in and explains the errors in my reasoning. And that is okay. I'm absolutely open to learning.

the worm

Thanks for the great input. Agree 2014 arc energy reduction was for CBc. In 2017 arc energy reduction was added to fuses with requirement effective January 1, 2020. I have contacted Schneider Electric and they currently have CBs to address 240.87; however they currently do not have a solution for 240.67 for fuses - maybe next year.